1. Field of Invention
The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for manufacturing a magnetic memory with self-aligned magnetic tunnel junction.
2. Related Art
Magnetic random access memory (MRAM) is a type of non-volatile memory, which is used to store and record information according to the resistance characteristic and has the advantage of non-volatility, high intensity, high read and write speed, anti-radiation, etc. The general method for writing data is to utilize two current lines, the bit line and write word line. A magnetic memory cell selected by the intersection of the bite line and the write word line through the magnetic field inducting, wherein the value of resistance is changed by transferring the magnetic direction of the ferromagnetic free layer. While reading data from MRAM, the current provided for the selected magnetic memory cell is applied to the resistance measuring of the selected magnetic memory cell to determine the digital value of the data.
The magnetic memory cell manufactured between the bit line and the write word line is a stack structure of multiple magnetic metal material layers, formed by stacking a soft ferromagnetic layer, a tunnel barrier layer, a hard ferromagnetic layer, an anti-ferromagnetic layer, and a nonmagnetic conductor. Through the parallel or anti-parallel magnetic direction between the two ferromagnetic layers stacked on two side of the tunnel barrier layer respectively, a bit is determined to be “1” or “0”. However, element failures often occur due to the difficulty in controlling the manufacturing process. Particularly, the contact area between the metal plug and the magnetic junction element is less than 0.05 μm; therefore, the magnetic junction element is often damaged, due to the etching resulted from the aligning deviation between the metal plug and the magnetic junction element, or due to the metal plug being bigger than the magnetic junction element. Thus, a short circuit finally occurs for the magnetic junction element.
With the technical trend that the element size and the memory area is being gradually reduced, one often encounters the difficulty in the overlaying contact between the magnetic junction element and the metal plug, which results in a short- circuit in the magnetic junction element.